In order to reduce operating costs, more and more operators choose to build a network together or rent a network of another operator. That feature is called GWCN (Gateway Core Network) in the 3GPP (3rd generation partnership project) standard. In an existing network, a user equipment may access an MSC (Mobile Switching Center)/VLR (Visitor Location Register) through a mobility management network element. Under the feature of the GWCN, the MSC/VLR serves multiple user equipments according to a circuit switched domain CS domain PLMN (public land mobile network) ID. In this case, the mobility management network element selects a CS domain PLMNID, and includes the selected CS domain PLMN ID in an LAI (location area identity) and sends the LAI to the MSC/VLR. The MSC/VLR stores the CS domain PLMN ID selected by the mobility management network element.
Currently, in a gateway core network (GWCN) or a multi-operator core network (MOCN), a mobility management network element sends, to an MSC/VLR, an LAI of a user equipment located, and after receiving the LAI sent by the mobility management network element, the MSC/VLR reads a PLMN ID in the LAI as a CS domain PLMN ID. Further, the MSC/VLR always stores the LAI sent by the mobility management network element, and allocates a TMSI to a user according to the LAI. The TMSI is unique within the LAI. The MSC/VLR further includes the LAI sent by the mobility management network element in a location update accept message and sends the location update accept message to the mobility management network element. In the prior art, an LAI sent by a mobility management network element to an MSC/VLR always includes an LAI including a CS domain PLMN ID. The CS domain PLMN ID may be used by the MSC/VLR in some non-specific processes. For example, a charging bill includes a CS domain PLMN ID which is reported to a billing center, or an information of the CS domain PLMN ID is provided during interaction with an HSS/HLR, so that the MSC/VLR obtains user subscription data related to the CS domain PLMN ID, and serves a user equipment according to the user subscription data. However, when the user equipment does not support network sharing, a location area identity LAI including a common public land mobile network identifier common PLMN ID is sent by the mobility management network element to the user equipment. The common PLMN ID is not equivalent to a CS domain PLMN ID, so that when the user equipment not supporting network sharing needs to access an MSC/VLR, it is caused that a message sent by the user equipment to the MSC/VLR is inconsistent with an LAI locally stored by the MSC/VLR, and therefore, the MSC/VLR determines to interact with an HSS (Home Subscriber Server) again to obtain data of the user equipment, and may perform re-authorization and authentication on the user equipment, which increases a time delay, and meanwhile, incurs unnecessary signaling, thereby causing a great waste of network resources.